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Unformatted text preview: billing (cab4763) – hw 1 – opyrchal – (121104) 1 This printout should have 8 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A plastic rod is rubbed against a wool shirt, thereby acquiring a charge of − 4 . 9 μ C. The charge on an electron is 1 . 6 × 10 − 19 C. How many electrons are transferred from the wool shirt to the plastic rod? Correct answer: 3 . 0625 × 10 13 . Explanation: Let : q = − 4 . 9 μ C = − 4 . 9 × 10 − 6 C and e = − 1 . 6 × 10 − 19 C . The total charge is q = n e e n e = q e = − 4 . 9 × 10 − 6 C − 1 . 6 × 10 − 19 C = 3 . 0625 × 10 13 . 002 10.0 points A particle of mass 13 g and charge 51 μ C is released from rest when it is 46 cm from a second particle of charge − 11 μ C. Determine the magnitude of the initial ac celeration of the 13 g particle. Correct answer: 1832 . 92 m / s 2 . Explanation: Let : m = 13 g , q = 51 μ C = 5 . 1 × 10 − 5 C , d = 46 cm = 0 . 46 m , Q = − 11 μ C = − 1 . 1 × 10 − 5 C , and k e = 8 . 9875 × 10 9 . The force exerted on the particle is F = k e  q 1  q 2  r 2 = m a bardbl vectora bardbl = k e bardbl vectorq bardblbardbl vector Q bardbl m d 2 = k e vextendsingle vextendsingle 5 . 1 × 10 − 5 C vextendsingle vextendsingle vextendsingle vextendsingle − 1 . 1 × 10 − 5 C vextendsingle vextendsingle (0 . 013 kg) (0 . 46 m 2 ) = 1832 . 92 m / s 2 . 003 10.0 points A particle with charge 9 μ C is located on the xaxis at the point − 10 cm , and a second particle with charge 9 μ C is placed on the xaxis at 6 cm . The Coulomb constant is 8 . 9875 × 10 9 N · m 2 / C 2 . 2 4 6 8 10 − 2 − 4 − 6 − 8 − 10 9 μ C 9 μ C 7 μ C x → (cm) What is the magnitude of the total elec trostatic force on a third particle with charge 7 μ C placed on the xaxis at − 2 cm ? Correct answer: 0 N. Explanation: Let : q 1 = 9 μ C = 9 × 10 − 6 C , q 2 = 9 μ C = 9 × 10 − 6 C , q 3 = 7 μ C = 7 × 10 − 6 C , x 1 = − 10 cm = − . 1 m , x 2 = 6 cm = 0 . 06 m , and x 3 = − 2 cm = − . 02 m ....
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This note was uploaded on 02/04/2011 for the course PHYSICS 121 taught by Professor Fayngold during the Spring '10 term at NJIT.
 Spring '10
 Fayngold
 Physics

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